Current interrupting plug or connecter



March 8, 1938. Q BARNES 2,110,255

CURRENT INTERRUPTING PLUG OR CONNECTER Filed March 12, 1936 2 Sheets-Sheet 1 invenior and 2 ifornc o March 8, 1938. H 0, BARNES 2,110,255

CURRENT INTERRUPTING PLUG OR CONNECTER Filed March 12, 1936 2 Sheets-Sheet 2 H is Q E invenlor H 0. Barnes QM M a A llorneya Patented Mar. 8, 19.38

PATENT OFFICE CURRENT INTERRUPTING PLUG OB NECTE I CON- B Harold 0. Barnes, Louisville, Ky. Application March 12, 1936, Serial No. 68,538

4Claims.

My invention relates generally to electrical plugs or connecters, and particularly to a plug or connecter containing means within itself to interrupt the current supply, and an important object of my invention is to provide an arrangement of this character which will operate upon the occurrence of a short circuit or upon the occurrence of an overload beyond the capacity the plug or connecter is built to carry in the appliance or circuit to which the plug or connecter is attached, so as to prevent the blowing out of the fuses in the pertinent supply line which would ordinarily occur.

Another important object of my invention is to provide a plug or connecter of the character indicated which includes a mercury current interrupter.

Another important object of my invention is to provide a plug or connecter of the character indicated which is simple and inexpensive'and which will last a long time without requiring adjustment or replacement.

Other important objects of my invention will be apparent from a reading of the following description in connection with the drawings, wherein for purposes of illustration I have shown a preferred embodiment of my invention.

In the drawings:-

Figure 1 is a general elevational view showing a plug in accordance with the present invention inserted in a wall socket or receptacle and having conductors extending from the plug to a domestic or other appliance.

Figure 2 is a side elevational view of a plug in accordance with the present invention.

Figure 3 is an end elevational view of Figure 2 taken from left to right.

Figure 4 is a horizontal sectional view taken through the plug showing the mercury in circuit making position.

Figure 5 is a view similar to Figure 4 but showing the mercury in'circuit breaking position.

Figure 6 is a transverse vertical sectional view showing the bolt holding the shell on the plug.

Referring in detail to the drawings, the numeral 5 generally designates a plug in accordance with the present invention which is adapted, as shown in Figure l, to be connected to a wall plug or receptacle 6 and to have extending from its opposite end the conduit I containing the conductors for energizing an appliance such as is generally exemplified at 8.

The plug comprises an outer shell 9 which is preferably of metal or other suitable material which encloses the dielectric material conforming body 10. The shell is drawn to a restricted opening II at one end and is entirely open at the end which is designated by the numeral l2, the lastnamed end being closed by a suitable dielectric washer l3 which the contact blades' l4 and I5 penetrate.

The contact blades l4 and I5 are arranged parailelly and have inwardly of the washer l3 heads IS on which are threaded shanks H which are engaged with conductive material anchors l3 which are located in the outer parts of bores l3 and 20. The bore l9 has anenlarged lateral extension 2| in which is located the conductive material anchor 22 into which is threaded the clamping screw 23 which clamps the conductor 24 for the wire 25.

A lateral extension 26 at the inward end of the bore 20 contains the conductive material anchor 21 into which is threaded the clamping screw 23 which clamps the conductor 23 of the wire 30. The anchor 13' has an extension 3| which is integral with the'anchor 26; whereas the anchor 13 has no such extension connected to the anchor 22, but the bore I3 is free of any conductive material between the anchor 22 and the anchor i3 and in this otherwise unoccupied portion of the bore i9 is normally located a quantity of mercury 32 which forms an electrical contact between the anchor I8 and the shank ll of the blade l4 and the anchor 22 and the screw 23.

The axially inward end of the bore 13 has a much reduced extension 33 which forms a relatively small duct which leads into the apex end of a conical reservoir 34 whose outer end is closed by a countersunk seal 35 closing the opening which traverses the right hand end of the body ill of the plug as clearly shown in Figures 4 and 5. The numeral 36 generally designates a bolt which traverses the body and engages the opposite sides of the covering or shell 3 so as to mount the shell on the body ill in properly connected manner. The mentioned reduced opening I acts as a guide for the wires 25 and 30.

The mercury 32 stays in the circuit making position shown in Figure 4 while the appliance and the lines leading thereto are in good condition, but when a short circuit occurs therein or an overload beyond the capacity of which the plug or connecter is intended to carry the mercury 32 becomes heated and expands to such an extent as to pass through the small duct 33 and arrive in the reservoir 34, so as to fail to any longer establish electrical connection between the blade l4 and the clamping screw 23, so that the current is interrupted through the plug. To replace the mercury in the bore is after the same has been driven in the manner indicated into the reservoir 34, it is only necessary to tap the blades I 4 and I5 on a surface while holding the plug in a position wherein the blades are dependent. The size or cross section of the bore l9 determines the amperage capable of being carried by the plug.

Although I have shown and described herein a preferred embodiment of my invention, it is to be definitely understood that I do not desire to limit the application of the invention thereto, and any change or changes may be made in the materials, and in the structure and arrangement of the parts, within the spirit of the invention and the scope of the subjoined claims.

What is claimed is:

1. A current interrupting plug comprising a dielectric body having a pair of blades extending from one end thereof, a conductor within said body and engaged with the inner end of one of said pair of blades, said conductor extending through one side of said body, said body being formed with a bore aligned with the remaining blade, and with a second and relatively small bore connected with the end of said bore, and with a tapered reservoir having its small end connected to said small bore, a quantity of mercury in said reservoir, the larger end of said reservoir opening through the end of said body, a closure closing said larger end of the reservoir, and contact means extending through a side of said body other-than the mentioned side and having its radially inward end exposed in said bore.

2. A current interrupting plug comprising a dielectric body having a pair of blades extending from one end thereof, a conductor within said body and engaged with the inner end of one of said pair of blades, said conductor extending through one side of said body, said body being formed with a bore aligned with the remaining blade, and with a second and relatively small bore connected with the end of said bore, and with a tapered reservoir having its small end connected to said small bore, a quantity of mercury in said reservoir, the larger end of said reservoir opening through the end of said body, a closure closing said larger end of the reservoir, and contact means extending through a side of said body other than the mentioned side and having its radially inward end exposed in said bore, said contact means comprising a tubular interiorly threaded bushing and a binding post screw threaded therein.

3. A current interrupting plug comprising a dielectric body having a pair of blades extending from one end thereof, a conductor within said body and engaged with the inner end of one of said pair of blades, said conductor extending through one side of said body, said body being formed with a bore aligned with the remaining blade, and with a second and relatively small bore connected with the end of said bore, and with a tapered reservoir having its small end connected to said small bore, a quantity of mercury in said reservoir, the larger end of said reservoir opening through the end of said body, a closure closing said larger end of the reservoir, contact means extending through a side of said body other than the mentioned side and having its radially inward end exposed in said bore, said contact means comprising a tubular interiorly threaded bushing and a binding post screw threaded therein, a portion of said conductor comprising a tubular interiorly threaded bushing having a binding post threaded therein.

4. A current interrupting plug comprising a dielectric body having a pair of blades extending from one end thereof, a conductor within said body and engaged with the inner end of one of said pair of blades, said conductor extending through one side of said body, said body being formed with a bore aligned with the remaining blade, and with a second and relatively small bo-re connected with the end of said bore, and with a tapered reservoir having its small end connected to said small bore, a quantity of mercury in said reservoir, the larger end of said reservoir opening through the end of said body, a closure closing said larger end of the reservoir, contact means extending through a side of said body other than the mentioned side and having its radially inward and exposed in said bore, said contact means comprising a tubular interiorly threaded bushing and a binding post screw threaded therein, a portion of said conductor comprising a tubular interiorly threaded bushing having a binding post threaded therein, and a casing enclosing said body, parts of said casing being radially spaced from the sides of the said body at and adjacent said bushings and binding posts to define guides for wires leading to the binding posts.

HAROLD O. BARNES. 

